A key aide to Gordon Brown has admitted destroying the careers of New Labour
Cabinet ministers by using dark arts to smear political opponents.

Damian McBride, Mr Brown’s former communications chief, said he discredited the former prime minister’s enemies by tipping off the media about drug use, spousal abuse, alcoholism and extramarital affairs.

In an autobiography that will cast a shadow over Labour’s party conference in Brighton next week, Mr McBride admits attempting to ruin the careers of the former home secretaries Charles Clarke and John Reid.

Mr McBride claims that he did it all out of “devotion” and “some degree of love” for Mr Brown, whom he describes as “the greatest man I ever met”.

The disclosures will cause acute embarrassment to Ed Miliband, the Labour leader, and Ed Balls, the shadow chancellor, who were allies of Mr Brown during his time in Downing Street.

In the book, serialised in the Daily Mail, Mr McBride claims that he helped to end Mr Clarke’s cabinet career by concocting a briefing war between him and a key adviser to Mr Blair.

The former spin doctor writes that he helped to force Mr Reid to quit his Cabinet post by leaking details of alleged “drinking, fighting and carousing”.

He confesses that he punished Ivan Lewis, then a junior minister, for criticising Mr Brown by leaking claims that he had been “pestering” a female aide. These claims were completely denied by Mr Lewis.

Mr McBride was forced to resign in 2009 for his part in an email plot to discredit senior Conservative ministers.

His disclosures were preceded by the release of hundreds of emails revealing the extent of the civil war between Tony Blair and Mr Brown.

One email suggested that Mr Brown told Mr Blair that he should resign because the public “hate him”. Another suggested that Mr Blair allowed members of his staff to describe the attempt to oust him as “blackmail”.

The emails were released by Benjamin Wegg-Prosser, a former director of the strategic communications unit under Mr Blair.

Mr McBride also uses his book to accuse Douglas Alexander, the current shadow foreign secretary, of failing to support his sister, Wendy, who was then the Scottish Labour leader. He writes that Mr Alexander “dispassionately” told Mr Brown that his sister would have to quit over an unlawful £950 donation.

Mr McBride refers in the book to the “art of leaking lies”. He conceded at one point that his treatment of Mr Lewis and the woman at the centre of the allegations was “cruel” and “vindictive”. He reveals that when Mr Brown was chancellor, he would log into his emails so that he could leak details of confidential government announcements to discredit rival ministers. He claims that ministers were oblivious and were left wondering who in their department was releasing information to the media.

Mr McBride also discloses that Mr Brown had a network of “moles” in other Whitehall departments.

He claims that in the dying days of Mr Brown’s premiership he attempted to recruit celebrity advisers to bolster his image including Simon Cowell, Lorraine Kelly, Fiona Phillips and Lord Sugar.

In the book, Mr McBride writes that he “completely lost his way” before his enforced resignation.

However, he appears to be unrepentant. He claims that there was an “unspoken” understanding between him and Mr Brown that the former prime minister would not question his methods.

Describing how he attempted to force Mr Reid to quit the Cabinet, Mr McBride says that he unearthed embarrassing details of the former home secretary’s past from his “black book”.

Meanwhile, the cache of Downing Street emails, handed to The Guardian, details the desperate attempts made by Mr Blair’s team to stop a rebellion designed to oust him from power or force him to give a date for his departure.

Mr Wegg-Prosser in one email described Mr McBride as “Damian McP---kface”. As Mr McBride emailed Downing Street asking whay they were accusing Mr Brown of orchestrating the attempted coup, Jonathan Powell, Mr Blair’s chief of staff, emailed colleagues telling them not to reply to “any of this ridiculous person’s ridiculous emails”.

In 2006 an email from Mr Wegg-Prosser to Anji Hunter, a former Downing Street aide, states: “GB kept demanding TB’s endorsement yet at the same time told that he had to leave office immediately cos the public hate him – weird or what.”